A. The Field of the Invention
The field of the present invention concerns apparatus and a method for delivering an additive liquid into a fuel flow during the time when the fuel is pumped from a supply tank to a holding tank.
B. Prior Art
Mixing of an additive to a home heating fuel has been practised for some time. Typically such additive is mixed during the time when the fuel is unloaded from a supply tank into a holding tank. This can take place at the depot when a tank truck is being loaded, or at the consumer's holding tank when the truck is being unloaded. The additive is supplied in very small amounts, typically in a proportion of one part additive to 3000 parts of fuel oil.
For example, an additive known as Actene A sold by Aetna Chemical Corporation is routinely added to fuel oil to improve burnability of the fuel oil, improve efficiency of the oil burner, reduce maintenance problems, and protect oil tanks from bacteria that coagulate fuel. This additive is relatively expensive and is desirably added in relatively small amounts to the fuel oil as the oil is being pumped from a source, such as a tank truck, to a commercial or consumer's fuel storage tank. For example, if fuel is being transferred from a tank truck to a storage tank at a flow rate of 70 gallons per minute, the additive is desirably added at the approximate rate of 0.02 gallons per minute.
Fuel pumping systems for the introduction of such additives are known in the art. One prior art device uses a turbine wheel arranged in the fuel oil flow as it is pumped from a source to a storage tank. This turbine wheel operates a pump, which in turn pumps additive into the fuel flow. Another prior art device uses a small piston pump driven by the pressure drop across a meter placed in the supply line. Additive is then pumped into the fuel in response to fuel flow through the meter.
These prior art pumping systems typically used for fuel oil systems are disadvantageous in that they have a tendency to clog, are expensive to install and maintain, do not perform well in cold weather, and are difficult to adjust so that a controlled amount of additive is introduced into the fuel at a fairly constant proportion regardless of the fuel flow rate.
Fluid proportioning devices are also known generally in the prior art. For example, U.S. Pat. No. 2,592,304 to Lubeley shows a device for proportioning the feed of one fluid into mixture with another fluid. U.S. Pat. No. 2,826,211 to Reed discloses apparatus for introducing additives into gasoline and other liquid fuels. U.S. Pat. No. 2,849,014 to Pressler et al. discloses an apparatus said to be capable of regularly discharging a small flow of liquid into a pipe or other channel in which there is a relatively large flow of liquid of a different kind and which will maintain the percentage or ratio of the two liquids substantially constant. Other such apparatus are disclosed in U.S. Pat. No. 3,647,002 to Lindsay and U.S. Pat. No. 4,354,516 to Newell.
U.S. Pat. No. 4,319,606 to Hoogenboom shows a fluid pressure regulator valve in which a spring valve is levered open and closed by an electromagnetic control coil. U.S. Pat. No. 1,760,315 to Nacket discloses a device using a spring valve said to provide airdilution of a gaseous mixture flowing through a manifold when the gaseous mixture stream has achieved sufficient velocity to deflect a spring valve.